# Siam Physics Congress 2015

20-22 May 2015
Asia/Bangkok timezone
The Centennial Celebration of General Relativity Theory and 80 Years of Thai Physics Graduate

## Structural phase transition of binary compounds of TlX (X = N, P, As) under high pressure : An $ab$ $initio$ Study

21 May 2015, 08:00
3h
Board: CON-03
Poster presentation Condensed Matter Physics

### Speaker

Kittipong Limchuchua (Mahidol Wittayanusorn School, Nakhon Pathom 73170, Thailand)

### Description

In this work, density functional theory (DFT) has been performed to investigate high-pressure phase transitions of TlX (X = N, P, As). Both standard GGA and LDA functionals with norm-conserving pseudopotential are used to compare each other in recent work which the calculation results are reported in form GGA (LDA). Based on the previous theoretical predictions, B3-to-B1 (B4-to-B1 for TlN) are reinvestigated initially, as well as the other candidates with crystal structure of *Cmcm*, *P4/mmm*, *Cmmm*, and B2-type structure are undertaken for comparing energetically to predict the high-pressure phases in these compounds. It reveals that TlN and TlP transform to B1 at 19 (16) and 28 (10) GPa, by compressing B4 and B3, respectively. The reduction volumes are approximately 14.8 (15.2) % and 14.7 (16.4) % for TlN and TlP, respectively. Moreover, B2-type is predicted at 340 (395) GPa for TlN, and at 97.5 (81) GPa for TlP with passing through *P4/mmm*. In TlAs, B3-type structure does not undergoes to B1-type. But it could possibly transform to *Cmcm* and *Cmmm* structure at which is different with previous predictions.

### Primary author

Kittipong Limchuchua (Mahidol Wittayanusorn School, Nakhon Pathom 73170, Thailand)

### Co-authors

Komsilp Kotmool (Department of Physics, Mahidol Wittayanusorn School, Nakhon Pathom 73170, Thailand) Mr Pornmongkol Jimlim (Department of Physics, Mahidol Wittayanusorn School, Nakhon Pathom 73170, Thailand) Mr Prutthipong TSUPPAYAKORN-AEK (Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand) Thiti Bovornratanaraks (Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand)

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